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Development and numerical implementation of an adaptive anisotropic soil constitutive modelling framework
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Dejaloud, Hesamoddin (2023) Development and numerical implementation of an adaptive anisotropic soil constitutive modelling framework. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3977810
Abstract
The reliable simulation of soil behaviour is critical for many geotechnical engineering applications, including the design of foundations, embankments, and underground structures. However, the complex nature of soils poses significant challenges when attempting to accurately predict their behaviour. This PhD thesis focuses on developing/validating a novel critical-state-based anisotropic constitutive modelling framework for clays, capable of capturing the complex characteristics of their response under different loading conditions. Establishing the constitutive modelling framework has begun with the development of an anisotropic constitutive model, AA1-CLAY. In addition to a flexible yield surface, AA1-CLAY has been equipped with an innovative rotational hardening (RH) rule to project the role of micro-scale fabric anisotropy on the overall behaviour. Developments towards enhancing AA1-CLAY with bounding surface plasticity theory to produce a more realistic representation of the nonlinear behaviour of clays with high OCR values have led to a new conception of a moving projection centre which helps to project the stress states to the correct side of the bounding surface. This formulation was first implemented into an extension of the well-known S-CLAY1 model, called BS-CLAY1. This model has led to development of a novel double image stress point (DISP) bounding surface model, called AA2-DISP. This model relates the plastic modulus of a stress state inside the yield surface to two image stress points using a weighted average method. Consequently, AA2-DISP is able to replicate complex monotonic/cyclic loadings with a minimum number of additional model parameters. Moreover, AA2-DISP signified how the critical state line (CSL) position participates in model simulations. Regarding this, an original concept of moving critical state, which is called a non-stationary critical state line (NCSL), has been developed and a novel state-parameter-based RH rule has been proposed to investigate the effect of fabric anisotropy on the critical state behaviour of clays. It is shown that the NCSL concept and its resultant RH rule, which are implemented into a new model, AA3-NCSL, can explain some of the distinctive pre-failure and critical state responses of clays. In this PhD thesis, the development from AA1-CLAY to AA3-NCSL is elaborated. The presentation of the models’ formulations is associated with extensive sensitivity analyses to investigate how model parameters participate in the model responses. Furthermore, all developed models are used to conduct simulations of different monotonic/cyclic tests on various clays reported in the literature.
Item Type: | Thesis (PhD) | ||||
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Subjects: | S Agriculture > S Agriculture (General) T Technology > TA Engineering (General). Civil engineering (General) |
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Library of Congress Subject Headings (LCSH): | Soil mechanics, Soil mechanics -- Mathematical models, Anisotropy, Clay soils | ||||
Official Date: | June 2023 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | School of Engineering | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Rezania, Mohammad | ||||
Format of File: | |||||
Extent: | xxii, 180 pages : illustrations | ||||
Language: | eng |
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